A lithium ion battery is a chemical power source commonly referred to as a secondary battery. Lithium batteries include a cathode formed from a compound able to reversibly intercalate and de-intercalate lithium ion, and an anode formed from another compound(s) able to reversibly intercalate and de-intercalate lithium ion. When the battery is changed, lithium ion is de-intercalated from its cathode and intercalated into its anode. The reverse takes place when the battery is discharged. A lithium ion battery basically comprises an electrode core and a nonaqueous electrolyte, both sealed in the battery case. The electrode core comprises a battery electrode comprising an anode, a cathode and a membrane used to separate the anode from the cathode. The cathode comprises a current collector and a cathode material coated on and/or filled in the current collector. The cathode material comprises a cathode active substance, a conductive additive and an adhesive.
Energy storage technology is recognized as a critical need for maintaining the quality of life in developed and developing nations. Demand for lithium-ion batteries (LIB) are rapidly increasing due to its application in wide range of devices such as cell phones, laptop computers, and camcorders, as well critical health applications such as a cardiac pacemaker where an energy source is required to assist regular heart-rhythm. Power needs are also critical for advanced military equipment, off-peak power for intermittent power generation sources including solar cells and wind generators, in electric vehicles, or space applications. The power source for these devices should possess high specific capacity (Ah/g) and density (Wh/g or Wh/l) that will make the batteries lighter and smaller, respectively.
The interfaces in cathode materials dictate numerous properties of electrode storage materials ranging from capacity loss, Li+ transport activation energy cost, as well as electrolyte stability and degradation products. An optimized interfacial layer that creates a stable transport interface is critical to the effective application of energy storage materials. The formation of controlled interfacial layers has not been systematically examined due to the typical architecture of the cathode element in battery components, which consist of carbon black, binder and active material powders. Active materials research is directed to bulk modifications through doping during synthesis processes, and the formation of controlled interfaces have not been addressed in detail. There are several cathode materials for lithium ion batteries known to have performance limits or progressive degradation due to reaction of the cathode material with the electrolyte to form a solid electrolyte interphase-like layer (SEI-like). Surface protection of nanoparticle cathode materials is used to improve overall battery performance, where the surface coatings are applied in a second synthesis step to the core particle synthesis. These coatings can be either organic (i.e. carbon) or inorganic ceramics (i.e. metal oxides).
In 1991, Sony commercialized the lithium rocking chair battery, which now is commonly known as lithium ion batteries. The pioneer introduction of LiCoO2 cathode in rechargeable (secondary) cell had a very high voltage and energy density during that period. But LiCoO2 batteries are expensive and are toxic. LiMn2O4 spinel is an excellent cathode material for the replacement of LiCoO2 because it is cheap, environmentally benign, exhibits good thermal behavior and a fairly high discharge voltage. However, LiMn2O4 has several disadvantages such as capacity reduction during charge-discharge (CD) cycle due to phase transition, and structural instability due to Mn dissolution in the electrolyte by acid attack. Hydrofluoric acid (HF) generated by the fluorinated electrolyte salts is one such example for Mn dissolution and is given as below,2LiMn2O4→3λ−MnO2+MnO+Li2O  (1)
However, manganese (through MnO) and lithium (through Li2O) dissolves into the electrolyte, which results in capacity fade at elevated temperature (40-50° C.), reducing battery performance.
The need remains, therefore, for a lithium battery having improved battery performance, and in particular, for a lithium battery cathode having high specific energy, good electrochemical cycling stability, electrode capacity, cycle life, good electronic conductivity, high lithium diffusivity, and chemical compatibility to the electrolyte, as well as low cost, safety, and a benign environment. The need also remains a need for a method of forming a lithium battery having improved battery performance, and in particular, for forming a lithium battery cathode having high specific energy, good electrochemical cycling stability, electrode capacity, cycle life, good electronic conductivity, high lithium diffusivity, and chemical compatibility to the electrolyte, as well as low cost, safety, and a benign environment.